This invention relates to the supply of electrical energy to AC loads from auxiliary power sources in a manner compatible with operation of the load by the energy normally available from an AC power distribution network.
The use of geophysical power sources typified by solar, wind and water turbines driving DC generators to augment the electrical power normally supplied from an AC distribution network by a power utility, is already well known. Such arrangements are presently being given more serious attention because of the rising costs of generating electrical energy and the growing concern with our inability to meet rising energy demands.
Utilization of energy having unipolarity voltage characteristics derived from auxiliary electrical power sources as aforementioned to operate an AC load that is otherwise operated by AC line voltage from a power distribution network, is disclosed in U.S. Pat. No. 3,946,242 to Wilkerson. According to the Wilkerson patent, the AC load is directly and continuously connected to the AC power mains in parallel with the output terminals of a thyristor bridge under control of switching circuits to which AC signals are supplied from the power mains so as to impart suitable voltage and frequency characteristics to the DC voltage energy at the output terminals of the bridge. Thus, according to the Wilkerson patent, energy to operate the AC load is continuously supplied from the AC power distribution network and only intermittently supplied from the DC voltage source through a logic controlled switching system. Such a power regulating system does not take into account the varying demand of the load nor regulate the relative amounts of energy consumed from the two energy sources to make full use of the energy available from the auxiliary DC voltage source.
It is, therefore, an important object of the present invention to provide a new and useful power regulating supply system for operating AC loads which will more effectively utilize the energy available from the auxiliary power source as well as to effect a greater savings in the amount of energy consumed from the AC power distribution network.